Underwater noise reduction system and deployment device using an open-ended resonator assembly

Abstract

A novel underwater noise reduction and deployment system is described. The system uses an inverted open-ended resonator (e.g., a Helmholtz resonator) to absorb underwater noise. The system includes a stackable resonator cavity embodiment that is arranged to operate around or near a noisy environment. The system can be deployed from a ship or barge or similar structure and can be stored when not in use.

Description

[0001] This application is a divisional application of the invention patent application with Chinese patent application number 201910167085.5 and invention name “Underwater noise reduction system and deployment device using open-end resonator components”; the invention patent application with Chinese patent application number 201910167085.5 is a divisional application of the invention patent application with Chinese patent application number 201480069475.4 and invention name “Underwater noise reduction system and deployment device using open-end resonator components” which was filed on December 16, 2014 as PCT international application PCT / US2014 / 070602 and entered the Chinese national phase on June 17, 2016. Technical Field

[0002] The present disclosure relates to the reduction of noise in noisy underwater environments including marine vessels, oil rigs, and other industrial and military applications.

[0003] Related Applications

[0004] PCT International Application PCT / US2014 / 070602 is derived from and claims priority to U.S. Provisional Application No. 61 / 917,343, filed on December 17, 2013, having the same title. Background Art

[0005] Some human activities cause underwater noise that propagates from underwater noise sources to the surrounding environment (sometimes many miles away). Underwater noise generated by oil and gas drilling platforms, ships and other human activities and machinery is generally considered to be undesirable. Some studies infer that underwater noise pollution can adversely affect marine life, and it can be destructive to other human activities (such as scientific, meteorological and military activities). This is particularly true for noise generating activities that cause large amplitude noise emission (loud sound) and propagation at frequencies that are sensitive to humans and marine life.

[0006] Vessels operating in environmentally sensitive or highly regulated areas may be restricted in how and when they can operate due to the noise generated by the vessels. This occurs in oil and gas fields where noise from mobile drilling vessels limits drilling times due to the effect it can have on migrating bowhead whales in the Arctic region. When a bowhead whale is observed, operations may be stopped until the bowhead whale has safely passed, and this process can take many hours.

[0007] As mentioned above, there are some concerns about the effects that ship traffic and other man-made noise have on marine mammals. Some studies have shown that man-made noise can have a significant effect on the stress hormone levels of whales, which could affect their reproductive rates, among other things.

[0008] Known attempts to reduce noise emissions from surface vessels include the use of so-called Prairie Maskers, which use multiple bundles of hoses that generate small free-rising bubbles to reduce the noise of the vessel. However, the small free-rising bubbles are generally too small to effectively attenuate low-frequency noise. In addition, the Prairie Masker system requires continuous pumping of air through the system, a process that itself generates harmful noise, consumes energy, and requires a complex gas circulation system that is expensive and cumbersome to the other operations of the vessel. Finally, such a system cannot operate below a given depth due to hydraulic forces and backpressures.

[0009] 7 One principle that is useful for approximating or understanding the acoustic effects of gas pockets in liquids (e.g., air pockets or bubbles or enclosures in water) is the behavior of spherical gas bubbles in liquids. The physical characteristics of gas bubbles are relatively well known and have been studied theoretically.

[0010] Figure 1 The diagram illustrates a model of a gas (e.g., air) bubble 10 in a liquid 15 (e.g., water). One model for studying the response of a gas bubble is to model a bubble of radius "a" as a mass on a spring system. The mass is "m", and the spring is modeled as having an effective spring constant "k". The radius of the bubble 10 will vary with the pressure felt at its walls, causing the bubble 10 to change size as the gas therein is compressed and expanded. In some cases, the bubble 10 may vibrate or resonate at certain resonant frequencies, similar to how a mass on a spring system may resonate at a natural frequency determined by the mass, spring constant, and bubble size.

[0011] Ongoing efforts to reduce the effects of underwater noise continue. While some approaches can actually reduce the amount of noise generated by a sound source, other approaches attempt to reduce the effects of noise by surrounding or partially surrounding the noise-making source with something that absorbs or otherwise attenuates the transmitted noise. Summary of the invention

[0012] The present disclosure is directed to the reduction of the severity of noise emissions from near noise generating objects or activities. The present concepts can be applied to man-made noise, but also more generally to any noise generated from a source underwater (e.g., in the ocean, coastal areas, drilling sites, lake beds, etc.).

[0013] Gas trapped in pockets beneath or around objects in the water can act as free bubbles and / or Helmholtz-like resonators, and thus work to attenuate noise in much the same way as resonant bubbles. To give an example of how this would work on a boat, a plate with hemispherical, cylindrical, conical (or similarly shaped) cavities could be attached to the hull of the boat, and when submerged, the pockets could be filled with gas via an external mechanical device or an internal manifold system. The properties of these pockets would be selected so that the gas trapped within each pocket resonates at or near the frequency we wish to attenuate (e.g., between about 30 Hz and about 200 Hz, including about 110 Hz), thereby maximizing its effectiveness. For an example of pile driving, a sheet or plate containing multiple such resonators could be deployed to fully surround the grinding portion of the pile. As in the previous example, the properties of the pockets would be selected to maximize the effectiveness of the system.

[0014] The system is customizable and can attenuate noise by a desired amount (e.g., 10 dB or more). The system can also be produced for specific target frequencies that are particularly loud. In other aspects, the present invention provides additional thermoacoustic absorption of sound through the selective application of a permeable mesh over the open end of the resonator.

[0015] One aspect of the present invention provides a stretchable resonator assembly for suppressing acoustic energy from a source in a liquid, the resonator assembly comprising: a hollow body having an open end, a closed end, and a side wall connected in sections, the side wall connected in sections having at least two segments, the at least two segments being stretchable from a folded position to an expanded position, the hollow body being capable of retaining gas when the resonator assembly is disposed in the liquid, wherein in the folded position, the at least two segments are folded in a first direction to reduce a length of the side wall in a second direction, the second direction being orthogonal to the first direction; and wherein, while the resonator assembly is immersed in the liquid, when the gas is disposed in the resonator assembly, in the expanded position, the at least two segments are expanded to increase the length of the side wall in the second direction.

[0016] In some embodiments, the open end has a first length and the closed end has a second length, the first length being different than the second length.

[0017] In some embodiments, the first length is greater than the second length.

[0018] In some embodiments, the sidewalls are rigid.

[0019] In some embodiments, the resonator assembly further includes a thermally conductive mesh disposed adjacent to the open end.

[0020] One aspect of the present invention also provides a stackable resonator system for suppressing acoustic energy from a source in a liquid, the resonator system comprising: a first resonator and a second resonator, each of the first resonator and the second resonator having a hollow body, the hollow body comprising an open end, a closed end, and a sidewall, wherein the open end has a first width in cross section and the closed end has a second width in cross section, the first width is different from the second width, the sidewall integrally connecting the open end to the closed end; and a coupling device, the coupling device connecting the first resonator and the second resonator; wherein the open end of the first resonator is stackable on the closed end of the second resonator in a storage position.

[0021] In some embodiments, the sidewall connects the open end to the closed end at an angle about a central axis passing through the open end and the closed end.

[0022] In some embodiments, the coupling device is segmented.

[0023] In some embodiments, the first resonator has a first resonant frequency and the second resonator has a second resonant frequency.

[0024] In some embodiments, the first resonant frequency is different from the second resonant frequency.

[0025] In some embodiments, the stackable resonator system further includes a conduit defined in the sidewall of the first resonator, the conduit adapted to transport a gas from the open end to the closed end of the first resonator.

[0026] One aspect of the present invention also provides a resonator assembly, the resonator assembly comprising: a first resonator, the first resonator having a first hollow body, the first hollow body comprising a first open end, a first closed end and a first side wall, when the first resonator is disposed in a liquid, the first hollow body can retain a gas; a second resonator, the second resonator having a second hollow body, the second hollow body comprising a second open end, a second closed end and a second side wall, when the second resonator is disposed in the liquid, the second hollow body can retain the gas; a conduit between the first resonator and the second resonator, the first resonator being fluidically connected to the second resonator through the conduit; a gas source, the gas source being fluidically connected to an inlet of the first resonator.

[0027] In some embodiments, the first resonator has a first resonant frequency and the second resonator has a second resonant frequency.

[0028] In some embodiments, the first resonant frequency is different from the second resonant frequency.

[0029] In some embodiments, the first resonant frequency is equal to the second resonant frequency.

[0030] In some embodiments, the catheter is rigid.

[0031] In some embodiments, the conduit is segmented.

[0032] In some embodiments, the gas source is in fluid communication with a manifold, and the manifold is in fluid communication with the inlet of the first resonator.

[0033] In some embodiments, the resonator assembly further includes a third resonator having a third inlet in fluid communication with the manifold, wherein the third resonator is substantially identical to the first resonator.

[0034] In some embodiments, the resonator assembly further includes: a fourth resonator in fluid communication with the third resonator, wherein the fourth resonator is substantially identical to the second resonator; and a second conduit between the third resonator and the fourth resonator.

[0035] In one aspect, the system includes a resonator having articulated sidewalls that reduce the length of the resonator in a storage configuration. In another aspect, the system includes a resonator that is stackable in a storage configuration to reduce space during transport, storage, and loading on a vessel, such as a piling vessel. In yet another aspect, the system includes a first resonator in fluid communication with a second resonator through a conduit. The first resonator can receive a gas through an inlet, wherein the gas can fill the internal volume of the first resonator and the second resonator through the conduit.

[0036] This system can allow operators to work for longer periods of time and in areas that were previously inaccessible due to noise regulation. Because each gas chamber is built so that the gas trapped inside will maximize the reduction of target underwater noise, this system is also much more efficient than current technology in reducing noise. In addition, it does not require energy or expensive support facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a fuller understanding of the nature and advantages of the present concept, reference is made to the following detailed description of preferred embodiments and in conjunction with the accompanying drawings, in which:

[0038] Figure 1A diagram illustrating a model of gas bubbles in a liquid according to the prior art;

[0039] Figure 2A and 2B illustrates a cross section of a collapsible resonator according to an embodiment;

[0040] Figure 3A and 3B illustrates a cross section of a stackable resonator according to an embodiment;

[0041] Figure 4A and 4B Diagrammatically illustrate the noise reduction system;

[0042] Figure 5A illustrates an exemplary resonator system in a deployed configuration;

[0043] Figure 5B illustrates an exemplary resonator system in a stacked configuration;

[0044] Figure 6 illustrates a plate of a resonator according to an embodiment;

[0045] Figures 7A-7C illustrates mechanical details of a gas-filled resonator according to an embodiment;

[0046] Fig. 8A and 8B illustrates a noise reduction device arranged in a stackable strip according to an embodiment; and

[0047] Fig. 9 An exemplary deployment system for an underwater noise reduction system is illustrated. DETAILED DESCRIPTION

[0048] Gas trapped in pockets beneath or around objects in water can act as free bubbles and / or like Helmholtz (or similar) resonators (e.g., Minnaert resonators and / or Church resonators), and thus work to attenuate noise in much the same manner as resonant bubbles.

[0049] The height of the internal volume of the cavity and its volume are configurable to suit the purpose under consideration. The hydrostatic pressure around the resonator varies with depth below the surface, and the size and / or shape of the cavity can be varied depending on their position with respect to the waterline on the face of the plate. Thus, as (in Figure 1 In the analogy of ) their spring constant can vary depending on the density and depth of the water surrounding them, the chamber can be designed to accommodate changes in the water pressure felt at the neck of the chamber due to the depth to which it is submerged.

[0050] In some embodiments, a mesh or other solid screen such as a metal mesh screen (e.g., a copper mesh screen) may be placed over the face of the plate. This may act to stabilize the air in the cavity. This may also act as a heat sink to dissipate heat energy absorbed by the resonant volume of the cavity and potentially improve its performance.

[0051] In some embodiments, a cavity of hemispherical or spherical or quasi-spherical cross-section is suitable for suppressing noise in the frequency range of use.

[0052] Figure 2A and 2B The diagram illustrates a cross section of an embodiment of a collapsible resonator 20. When not deployed in water 25, since the resonator 20 will be stored and transported, Figure 2A The resonator 20 in FIG. 2 is shown in a stacked form. The resonator 20 has a hollow body 200 including an optional circumferential portion 220 connected to a segment sidewall 230. The hollow body 200 has a closed end 240 and an open end 250. The closed end 240 is generally equivalent to the segment sidewall 230 and the optional circumferential portion 220.

[0053] As illustrated, the segment sidewall 230 is folded in a first direction 260 (e.g., similar to an accordion) to reduce the length of the segment sidewall 230 in a second direction 270. The second direction 270 is orthogonal to the first direction 260. However, it is noted that other relative orientations of the first direction 260 and the second direction 270 fall within the scope of the present invention and are a matter of design choice. The segment sidewall 230 includes a first sidewall 232 and a second sidewall 234. The first sidewall 232 is shorter than the second sidewall 234 to reduce the length of the segment sidewall 230 along the first direction 260. When the resonator 20 is in a collapsed or stored configuration, the first direction 260 can be parallel to the first sidewall 232. In some embodiments, the first sidewall 232 can have a length equal to or greater than the second sidewall 234. The segment sidewall 230 can be formed of a rigid material, or can have a rigid frame (e.g., aluminum) with a flexible material (e.g., neoprene) on the walls defined by the frame. Alternatively, the segmented sidewall 230 may be a flexible material.

[0054] As when deployed in water 25, Figure 2B25. The resonator 20 in the embodiment of the present invention is shown in an extended form. As the resonator 20 is submerged in the water 25, the resonator 20 captures air or a buoyant fluid in the interior 290 of the hollow body 200. Additionally or alternatively, gas may be introduced into the hollow body 200 from a gas source (not shown), such as a gas tank. The buoyancy of the air (or buoyant fluid) in the interior 290 of the hollow body 200 creates a force on the segment sidewalls 230, causing the segment sidewalls 230 to expand in the second direction 270, thereby increasing the length of the segment sidewalls 230 in the second direction 270. As the length of the segment sidewalls 230 in the second direction 270 increases, like a parachute, the volume of the hollow body 200 also increases. Due to the reduced volume of the hollow body 200, the volume is filled with air but the air is at a reduced pressure. Alternatively, the volume is filled with a fluid having a higher buoyancy than the water 25.

[0055] As illustrated, Figure 2B The resonator 20 in the embodiment of the present invention looks like an inverted cup with an interface 295 between the water 25 and the air (or buoyant fluid) in the cup. The interface 295 is near the open end 250 of the hollow body 200. The resonator 20 can act like a Helmholtz resonator (or other resonator, such as a Minerdt resonator and / or a Church resonator) and can have a resonant frequency as discussed above. The interior 290 of the resonator 20 can have a volume of approximately (i.e., within 10%) 2670 cubic centimeters.

[0056] Figure 3A and 3B Illustration similar to the above Figure 2A and 2B Another exemplary embodiment of a resonator of the present invention is described in conjunction with the embodiment described above. However, a mesh 310 that is substantially permeable to fluid flow has been attached to the open end 350 of the resonator 30. As mentioned above, the mesh 310 may be formed of a screen having thermally conductive properties.

[0057] Figure 4A and Figure 4B The diagram illustrates a noise reduction system 40 including a plurality of stackable inverted cup-shaped resonator bodies 400, each resonator body 400 having a downwardly facing open end 410. Thus, each of the resonators 400 can be designed as described above with respect to Figure 2A-2B and Figure 3A-3B When the system 40 is stored, transported, or in air above water (e.g., as Figure 4A ), the resonator is in its folded state. Thereafter, once deployed in water 25 (e.g., as Figure 4B), as the resonators 400 fill the floating air above, the plurality of resonators 400 expand to their operational size and shape. The plurality of resonators 400 may be formed on or in the plate 420 in a manner similar to a venetian blind (e.g., as an array of resonators 400) to simplify deployment. The resonators 400 may be formed of a rigid material, or may have a rigid frame (e.g., aluminum) with a flexible material (e.g., neoprene) on the walls defined by the frame. Alternatively, the resonators 400 may be formed of a flexible material.

[0058] Figure 5A An exemplary resonator system 50 is illustrated in a deployed configuration. The resonator system 50 has a plurality of stacked or stackable resonator bodies 500A, 500B, 500N (generally referred to as resonator bodies 500) in the form of pyramids. Note that the resonator bodies 500A, 500B, 500N may be other shapes (e.g., pyramidal, hemispherical, etc.), and Figure 5A and 5B The cone shape illustrated in is illustrative only. At least one coupling device 510 connects adjacent resonator bodies (e.g., 500A and 500B). The coupling device 510 is segmented to flexibly connect one resonator body (e.g., 500A) to another (e.g., 500B). In some embodiments, the coupling device 510 is flexible, retractable and / or segmented. Alternatively, the coupling device 510 can be rigid.

[0059] The resonator body 500 has an open end 520 and a closed end 530. The resonator body 500 is hollow and generally tapers from the open end 520 to the closed end 530. The open end 520 has a first width (e.g., diameter) 525 and the closed end 530 has a second width (e.g., diameter) 535. Because the resonator body 500 is shaped like a cone, the first width 525 is greater than the second width 535. However, in some embodiments, the first width 525 is less than the second width 535. Thus, generally, the first width 525 is not equal to the second width 535. The resonator body 500 can be formed of a rigid material, or can have a rigid frame (e.g., aluminum) with a flexible material (e.g., neoprene) on the walls defined by the frame. Alternatively, the resonator body 500 can be formed of a flexible material. The resonator 500 can have an internal volume of about (i.e., within 10%) 220 cubic centimeters.

[0060] Figure 5BThe diagram illustrates a resonator system 50 in a stacked or superimposed configuration. In this configuration, the open end 520 of the first resonator body 500A is stacked and / or nested on top of the closed end 530 of the second resonator body 500B, and the coupling device 510 is in a folded / bent configuration. The first resonator body 500A partially covers the second resonator body 500B. Since the resonator system 50 is more flexible along the central axis 590 than the resonator system 50 in the deployed configuration ( Figure 5A ) is more compact, which is beneficial for storage. The central axis 590 passes through the open end 520 and the closed end 530 of the resonator body 500 and forms an angle 570 (ie, in addition to 180 degrees) with the tapered sidewall 580 of the resonator body 500.

[0061] As discussed above, the first resonator 500A and the second resonator 5000B have respective resonant frequencies. In some embodiments, the first resonator 500A has a first resonant frequency that is different from a second resonant frequency of the second resonator 500B. Alternatively, the first resonator 500A and the second resonator 5000B can have the same or substantially the same (i.e., within 10%) resonant frequencies. The resonant frequencies can be between about 30 Hz and about 200 Hz, including about 110 Hz.

[0062] In some embodiments, one or more conduits 540A, 540B, 540N (generally referred to as conduits 540) are defined on or in the stackable resonator bodies 500A, 500B, 500N, respectively. The lower open end 502 of the conduit 540 (e.g., a vent) is disposed at or near the open end 520 of the resonator body. The upper open end 504 of the conduit 540 is disposed at or near the closed end 530 of the resonator body 500 and below the adjacent resonator 500. In operation, a gas (e.g., air) is bubbled into the open end 520 of the hollow resonator body 500N. The gas may be supplied from a gas source (e.g., a compressed gas tank). The gas bubbles rise toward the closed end 520 of the hollow resonator body 500N and subsequently fill the hollow resonator body 500N from the closed end 530 of the hollow resonator body 500N to the open end 520. When the hollow resonator body 500N is filled with gas, the air is at or near the open end 520 of the hollow resonator body 500N. The gas then flows from the lower open end 502 to the upper open end 504 of the conduit 540N into the conduit 540N on the resonator body 500N. The gas then bubbles into the next resonator body 500B immediately above the resonator body 500N. The same process can be repeated until all resonator bodies 500 along the vertical axis are filled with gas.

[0063] Figure 6A plate 60 of resonators 600 illustrated in an embodiment. The resonators 600 are arranged in an array of X resonators 600 horizontally and Y resonators vertically (e.g., in columns). In some embodiments, the array includes an additional dimension of Z resonators 600 in a direction orthogonal to the horizontal and vertical directions. Each resonator 600 has a first end 610 and a second end 620 and has a hollow body as discussed above. The resonator 600 is generally in the shape of an inverted bulb (e.g., a light bulb), but it can be in any shape suitable for capturing and retaining gas. The first end 610 can be open or partially open to the surrounding water 25 environment. The resonator 600 can be formed of a rigid material, or can have a rigid frame (e.g., aluminum) with a flexible material (e.g., neoprene) on the walls defined by the frame. Alternatively, the resonator 600 can be a flexible material.

[0064] like Figure 6 As illustrated, in a vertical direction, a conduit 630 connects adjacent resonators 600 (through respective first ends 610). Through the conduit 630, the first resonator 600A is in fluid communication with the second resonator 600B, wherein the second resonator 600B is disposed below the first resonator 600A. Gas may be introduced into the first end 610 of the first resonator 600A through an inlet. The inlet is connected to a manifold 650, which in turn is connected to a gas source 660. Alternatively, the inlet 640 is directly connected to the gas source 660, which may be a source of compressed gas.

[0065] As discussed above, the first resonator 600A and the second resonator 600B have respective resonant frequencies. In some embodiments, the first resonator 600A has a first resonant frequency that is different from the second resonant frequency of the second resonator 600B. Alternatively, the first resonator 600A and the second resonator 600B can have the same or substantially the same (i.e., within 10%) resonant frequencies. The resonators 600 across the array can be the same, substantially the same, or different from each other.

[0066] In operation, a gas (e.g., air) is pumped or otherwise introduced into the inlet of the first resonator 600A through the manifold 650. The gas fills the hollow body of the first resonator 600A and displaces the fluid (e.g., water) in the hollow body. The fluid flows toward the second resonator 600B through the conduit 630. Alternatively, the fluid flows through a vent or valve in the first end 610 of the first resonator 600A. After the gas creates a threshold pressure in the first resonator 600A, the gas displaces the fluid in the conduit 630 and in the second resonator 600B, thereby filling the second resonator 600B with the gas. This process continues for the Y conduit 600 in the vertical direction (e.g., through resonators 600C, 600D, and 600E). In this orientation, the gas will naturally flow vertically toward the surface 35 of the water 25 due to the buoyancy of the gas. The fluid displaced by the gas in the resonators 600A, 600B, etc. may be purged into the water 25 through a valve or the like.

[0067] Figures 7A-7C Illustrated are mechanical details of a gas-filled resonator 700 in a plate 710 suitable for supporting multiple resonators to cancel underwater noise, such as with respect to Figure 6 as described. Fig. 7A Shown is a cutaway cross section of the hollow body 770 of the resonator 700. The inlet 740 and outlet / conduit 730 are optionally connected to another such resonator (not shown). Figure 7B The figure illustrates a first perspective view of the resonator 700 in the support plate 780, and Figure 7C Yet another perspective view of the resonator 700 is illustrated.

[0068] In some embodiments, the walls 720 of the resonator 700 are soft and / or flexible, while the plates 710 are rigid. The soft and / or flexible walls 720 allow the resonator 700 to be stackable during storage. For example, the plates 710 (which may include an array of resonators 700) may be stored by stacking multiple plates 710 on top of each other or by winding the plates 710 around a bobbin. In either case, if the walls 720 of the resonator 700 are stackable, the plates 710 may be stored more efficiently and / or compactly.

[0069] This invention is not limited to use in surface or sub-surface vessels and ships, but can be used by oil and gas companies drilling in the ocean (e.g., on drilling rigs and barges), offshore power generation activities (e.g., piling activities from the installation of wind farms), and in bridge and pier construction or any other man-made noise generating structure.

[0070] As for applications of the present system, one may prepare a plate similar to those described above for attachment to a submerged structure or vessel. The plate may include a plurality of gas (e.g., air) cavities, wherein the buoyancy of the air in the water environment causes the air to be retained within the cavities. The cavities may be filled by the action of an inverted submersion of the plate or structure (e.g., with the open side of the resonator directed downward toward the ocean floor). Alternatively, the cavities may be actively filled using an air source disposed below the cavities, such that air from the source may rise into the cavities and subsequently be retained therein. The cavities may need to be replenished with gas from time to time.

[0071] In some embodiments, a gas other than air may be used to fill the cavity. The temperature of the gas in the cavity may also affect its performance and resonant frequency, and so in some embodiments this may also be modified.

[0072] Fig. 8A and 8B An exemplary side view and top view cross section of a noise reduction device 80 are illustrated, respectively, which is arranged in a stackable strip that can be deployed from an offshore platform by a deployment system. The noise reduction device 80 includes conical resonators 800, which are coupled to each other in a stackable manner by gas pipelines 810. Each resonator 800 has a flexible resonator and a stainless steel extension ring 820. The stack can also be equipped with air, power, communication and other fluid and electronic signal pipelines 840. A smooth outer sheath 850 covers the stack of resonators. Reinforcement 830 (e.g., a fire hose like a tube or inflatable structure) can provide mechanical rigidity to the system. As shown, if necessary, a pull cable 860 can be included to provide counterweight.

[0073] Fig. 9 An exemplary deployment system 90 for a water noise reduction system 900 is illustrated. The system 90 can be deployed from a barge boom 910 supporting a resonator bar 920 guided by belts and rollers 930. The resonators are stored and deployed from rollers 940, which in an exemplary embodiment can be stacked to approximately 8 feet by 16 feet. Ballast 950 can be used if necessary to assist in lowering the noise reduction resonator system 900 into the water. A maneuverable counterweight base, air supply, camera, thrust member, and other components for moving and positioning the system (collectively 960) are included and coupled to the platform tower structure.

[0074] Many other designs may be developed for the purpose of noise reduction and suppression. In other embodiments, the resonant cavity may be filled with a liquid fluid instead of a gas fluid. For example, as will be appreciated by those skilled in the art, if the system is to operate at extreme depths in the ocean, liquids other than water having a different compressibility than seawater may also be used.

[0075] Upon reading this disclosure, those skilled in the art will appreciate that the concepts presented herein can be generalized or specialized to a given application at hand. Thus, this disclosure is not intended to be limited to the exemplary embodiments described, which are given for illustration purposes. Many other similar and equivalent embodiments and extensions to these concepts may also be included herein. The claims are intended to cover such modifications.

Claims

1. A resonator assembly, comprising: a first resonator having a first hollow body, the first hollow body comprising a first open end, a first closed end, and a first sidewall, the first hollow body being capable of retaining a gas when the first resonator is disposed in a liquid; a second resonator, the second resonator having a second hollow body, the second hollow body comprising a second open end, a second closed end, and a second sidewall, the second hollow body being capable of retaining the gas when the second resonator is disposed in the liquid, the second resonator being vertically positioned above the first resonator along a vertical axis, wherein the first open end and the second open end are configured to be oriented downwardly toward a bottom of the body of water; a conduit between the first resonator and the second resonator, the first resonator being in fluid communication with the second resonator through the conduit; a source of compressed gas in fluid communication with an inlet of the first resonator, the source of compressed gas being configured to displace liquid in the first hollow body, in the conduit, and in the second hollow body to subsequently fill the first hollow body, the conduit, and the second hollow body with compressed gas.

2. The resonator assembly of claim 1, wherein the first resonator has a first resonant frequency and the second resonator has a second resonant frequency.

3. The resonator assembly of claim 2, wherein the first resonant frequency is different from the second resonant frequency. The resonator assembly of claim 3 , wherein the first resonant frequency is equal to the second resonant frequency.

5. The resonator assembly of claim 1 wherein the conduit is rigid.

6. The resonator assembly of claim 1, wherein the conduit is connected in sections.

7. The resonator assembly of claim 1, wherein the source of compressed gas is in fluid communication with a manifold, the manifold being in fluid communication with the inlet of the first resonator.

8. The resonator assembly of claim 7, further comprising a third resonator having a third inlet in fluid communication with the manifold, wherein the third resonator is substantially identical to the first resonator.

9. The resonator assembly of claim 8, further comprising: a fourth resonator in fluid communication with the third resonator, wherein the fourth resonator is substantially identical to the second resonator; as well as A second conduit is provided between the third resonator and the fourth resonator.

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